This invention relates to silver halide emulsions wherein the silver halide is comprised of non-tabular grains. More specifically, this invention relates to spectral sensitizing dyes specifically designed to increase the blue sensitivity of said silver halide elements and the relative emulsion speed thereof. Still more particularly, this invention relates to blue sensitive, gelatino silver halide emulsions that can be used in conjunction with specific X-ray intensifying screens to improve the output therefrom.
The prior art teaches the use of blue sensitizing dyes with tabular grain emulsions since these emulsions are not particularly sensitive in this spectral region. Thus, in tabular silver halide elements designed specifically for use in the field of X-ray, it is conventional to add some sort of blue sensitizing dye to this emulsion to increase the sensitivity within this region. Although in the past, blue sensitizing dyes have been added to emulsions made using regular, spherical-type silver halide grains, for example, these dyes have usually been added for a specific purpose. For example, certain films designed for exposure to laser generated images have a dye sensitive in the blue region of the spectrum (e.g. from about 450 nm to about 490 nm), added thereto. However, it is generally not conventional to add sensitizing dyes to standard emulsions since they already possess considerable sensitivity in the blue region and there would be no particular advantage for this addition. However, with the increasing presence of alternative light sources emitting energy in this blue region, there is a pressing need to insure that the emulsions have the requisite sensitivity to record images when exposed thereto. This is especially prevalent in the area of X-ray since there are now higher speed phosphors which have recently been discovered. Thus, there is a need to have silver halide elements which are sensitive to the light output of these phosphors.